1. Technical Field of the Invention
This invention is an article of manufacture. The invention broadly relates to an article of manufacture useful to support, store and aid in the transport of a load. The invention further relates to a platform that facilitates the storage and support of goods. The invention still further relates to a platform that facilitates the transportation from one location to another of goods supported and stored on the platform. The invention more specifically relates to a pallet.
2. Description of the Prior Art and Problems Solved
Persons involved in the art of material handling, such as manufacturers, shipping agents, warehouse operators, retailers and others, have long relied on platforms for supporting, storing, handling and shipping a wide variety of items, such as natural products and manufactured goods. Such platforms are known to be standard in shape and dimension and are referred to in the art as pallets. In a broad sense, pallets are ordinarily rectangular in shape and consist essentially of a storage deck and a support deck, wherein the storage deck and the support deck are spaced apart by, and rigidly connected to, an open frame. Goods are placed on the storage deck and the support deck is placed on some base, such as the ground, a rack system, as described below, or on some other pallet. The open frame employed to connect the storage deck to, and separate it from, the support deck thereby defines a space having sufficient distance between the decks to enable the insertion of lifting arms or tines into the defined space to facilitate lifting and moving the pallet and the goods stored and supported thereon. Such lifting arms can be those usually associated with pieces of equipment known in the art as forklifts and pallet jacks.
Pallets having goods placed thereon can be, and preferably are, stored in accordance with a method designed to maximize the use of available floor space. The art has, thus, developed a rack system which broadly features facing pairs of vertically extending columns. Each pair of columns is connected by a multiplicity of horizontal, vertically spaced, inwardly extending ledges to produce a vertical frame which resembles a ladder having multiple treads. Each horizontal ledge, i.e., each tread, faces, and is in alignment with, a horizontal ledge which is similarly connected to an opposite pair of vertically extending columns. The aligned horizontal ledges lie in the same horizontal plane. The horizontal separation between facing pairs of columns is substantially equal to or perhaps slightly greater than the width dimension of a pallet to thereby enable a pallet to be positioned between adjacent pairs of facing columns, wherein one edge of the pallet is supported by one of the mentioned inwardly extending ledges and the opposite edge of the pallet is supported by the aligned ledge on the opposite pair of columns. This method of storage has been referred to as open edge rack storage of loaded pallets. The rack system employed in this method has been referred to as an open rack drive-through system and pallets employed in the method have been referred to as rackable pallets.
It is evident that the entire weight of goods stored on a rackable pallet placed in an open rack drive-through system is supported between the two opposite edges of the pallet which are in contact with the mentioned ledges of the rack system. Accordingly, such a pallet must possess strength sufficient to support a substantial weight of goods placed on the storage deck thereof while preventing unacceptable bending or sagging, i.e., deflection, of the pallet between the supported edges.
A pallet is subject to rough handling over its useful life. The pallet must, therefore, possess sufficient flexibility to absorb impact in both cold and hot conditions without becoming brittle which could result in a shortened life.
A pallet not having goods placed thereon must sometimes be manually handled by an individual. Accordingly, the weight of the pallet itself becomes an important consideration from the view point of human labor required to safely handle it. In this regard, current government standards require two people to lift items weighing more than 50 pounds.
In view of the deflection and labor problems expressed above, a pallet to be placed in a standard open rack drive-through system is preferably about 48 inches long and about 40 inches wide. Furthermore, a pallet preferably weighs less than about 50 pounds and is preferably capable of supporting a load of about 2800 pounds while exhibiting minimal deflection at a point intermediate the supported edges thereof while in a standard open rack drive-through system.
In addition to the problems of weight and strength discussed above, a desirable pallet is durable and thus can endure the rigors of use over an extended period of time. Furthermore, a desirable pallet can be easily assembled after delivery to a point of use and can be repaired with spare parts. A desirable pallet can be conveniently cleaned to maintain the pallet in a sanitary condition.
It is, accordingly, clear that important problems involved with pallets include: weight, which is influenced by the quantity and type of material employed in the construction of the pallet; strength, which is influenced by the geometry and type of material employed in the construction of the pallet; flexibility and durability, which is influenced by the type of material employed in the construction of the pallet; cleanliness, which is influenced by the type of material employed in the construction of the pallet; and repairability, which is influenced by the design of the pallet and the relationship of the parts thereof.
The prior art has long experienced the use of wooden pallets. Wooden pallets, while being strong and providing satisfactory deflection properties, are, nevertheless, quite heavy and not easily handled by a single person. The useful life of a hard wood pallet is believed to be limited to a period of about five to eight shipments. Wooden pallets tend to splinter and break over the period of use.
The prior art has long sought to produce pallets which can provide the desirable features mentioned above and which can avoid the undesirable features of wood. Accordingly, Hale et al in U.S. Pat. No. 6,109,190 disclose a two-piece, snap-together, rackable pallet constructed of plastic materials, wherein the pallet can be repaired. Furthermore, the pallet of Hale et al can be constructed of different types of plastic material to meet the differing needs of each of the two pieces included in the pallet.
In addition, LeTrudet (U.S. Pat. No. 6,029,583), Apps et al (U.S. Pat. No. 6,006,677), John et al (U.S. Pat. No. 5,887,529), Pigott et al (U.S. Pat. No. 5,579,686), Gonzales et al (U.S. Pat. No. 5,497,709), and Kreeger (U.S. Pat. No. 4,597,338) each disclose pallets comprised of a plastic upper member attached to a plastic lower member. The essential differences between these patents reside in the mode of separation of the upper member from the lower member and the mode of attachment of the upper member to the lower member.
Thus, LeTrudet features a system wherein protruding legs integral with the lower member are adapted to snap into openings in protruding legs integral with the upper member.
Apps et al feature a system wherein protruding legs integral with the lower member snap fit into recesses in the upper member.
John et al feature an intricate system comprised of a multiplicity of modular components which are interlockably assembled to form a pallet. More specifically, the pallet of John et al comprises an upper member comprised of four interlocking pieces and a lower member comprised of six interlocking rails to form a grid, wherein the upper and lower members are separated by spacing members which interlock with the upper member components and the lower member components.
Pigott et al disclose an intricate system of attaching an upper member to a lower member by a combination of six separate and six integral spacers which operate to connect the respective surfaces by a snap lock method. Pigott et al disclose that the separation between connectors is not uniform for the purpose of minimizing deflection caused by loading.
Gonzales et al disclose a pallet having a locking scheme for snapping an integral part of the upper member to an integral part of the lower member. The respective integral parts are, accordingly, in direct contact and also function to provide space between the upper member and the lower member. In one aspect, Gonzales et al disclose discontinuous vertical ribs extending upwardly from the outside edges of the lower member which are adapted to fit into discontinuous slots extending downwardly from the outside edges of the upper member.
Kreeger discloses a pallet having an upper member which is identical to a lower member. The upper and lower members are connected by parts integral to each member which project vertically from each member. The vertically extending parts contact each other, provide space between the upper member and the lower member and are adapted to form interlocking snap-fit latches.
Allgeyer et al. (U.S. Pat. No. 3,757,704) discloses a pallet consisting of at least two separate pieces of material including an upper plastic piece and a lower plastic piece which are in peripheral contact each with the other. The upper plastic piece and the lower plastic piece are sealed together and can cooperate to enclose a third plastic intermediate piece between the upper piece and the lower piece. In addition, a planar reinforcing piece can be inserted between the upper piece and the intermediate piece to add additional strength to the pallet.
In view of the described problems and desires of the prior art and some attempts made in the prior art to solve those problems and satisfy those desires:
It is an object of this invention to provide a pallet having strength sufficient to permit storage of goods placed on the pallet in an open edge rack storage system.
It is also an object of this invention to provide a pallet which can be shipped in pieces and then easily assembled at the point of delivery.
It is also an object of this invention to provide a pallet which can be repaired with replaceable parts.
It is also an object of this invention to provide a pallet which can be configured to provide variable distances between the upper member of the pallet and the lower member of the pallet.
It is also an object of this invention to provide a pallet having a weight which will permit it to be conveniently handled by one person.
It is also an object of this invention to provide a pallet which is durable and which can be maintained in a sanitary condition.
Disclosure of the Invention
This invention is an article of manufacture useful for supporting, storing and transporting a load. The article is comprised of at least two, and can include three, separate planar parts, which enable the article to be repaired by convenient replacement of used and/or worn parts with, for example, new parts. The article of this invention is strong and resists deflection under loading; it is flexible and resists impact and is light in weight.
The article, in one embodiment, is comprised of a planar deck component having a flat surface adapted to contact and support a load during static storage of the load as well as during transport thereof. The deck has strength sufficient to support a load during storage as well as to resist dynamic forces encountered during operations conducted to place the load on, and to remove the load from, the deck and during operations conducted to lift and transport the load. The deck, accordingly, possesses at least two principal properties, one of which is that it is stiff enough to support an imposed load without exhibiting unacceptable deflection, and the second of which is that it is flexible enough, i.e., not brittle, to resist abrasive and impact forces without breaking or cracking. As is more particularly described below, the deck is comprised of a load contacting element, referred to as a tray, and a load support element, referred to as a structural insert, wherein the structural insert is comprised of ribs which are adapted for insertion into slots which are integral parts of the tray.
The article, in a second embodiment, comprises the deck component of the first embodiment removably connected to a support component comprised of a planar base member, a plurality of discrete vertical legs and a plurality of mechanical fasteners. The base member is removably connected to the deck by the mentioned legs and mechanical fasteners. The legs and fasteners not only function to connect the deck to the base, but also operate to separate the deck from the base. Accordingly, the distance between deck and base can be easily varied by using legs of different length.
The article of this invention can be employed in a variety of services which require a load bearing surface, such as in floors and roof decking. However, a preferred use of the article is as a pallet for storing retail goods, such as foodstuffs, in vertical open frameworks, referred to as racks. It is well known that such racks are designed to support a large number of pallets in vertical columns, wherein each pallet in a vertical column is supported on two opposite edges by inwardly extending ledges which are load contacting components of the mentioned frameworks.
The article of manufacture of this invention, when in the pallet configuration, offers a variety of benefits. The pallet can be quickly disassembled for repair and replacement of component parts, including the tray, structural insert, base and legs. The pallet can be shipped in unassembled condition to thereby conserve shipping space, or conversely, to increase the number of units which can be shipped in a given shipping volume. The physical and chemical properties of the pallet as a whole can be manipulated by use of different materials of construction to adjust weight, strength, temperature sensitivity, and abrasive, chemical and flame resistance. The dimensions, geometric shape and the number of the mentioned ribs and slots can vary, depending on pallet size and load requirements.
The above mentioned deck of this invention, as previously alluded to, is comprised of an array of at least two, separate, nested, stacked and aligned planar parts each of which is removable from and replaceable in the array. The first of the at least two planar parts of the deck is the load contacting portion thereof, which is referred to herein as a tray. The second of the at least two planar parts of the deck is the auxiliary support portion thereof, which is referred to herein as a structural insert.
The above mentioned tray consists of an upper, i.e., an exposed, side which is adapted to contact a load, and a lower, i.e., an obvert, side which is adapted to help stiffen the tray and, more importantly, to nestably receive, substantially conceal, protect and provide lateral support to, the elements of the structural insert nested therein. The exposed side of the tray is a flat surface having a plurality of holes formed there through to permit liquid to pass through the deck and to help reduce the weight of the tray without damaging the structural integrity thereof. The obvert side of the tray is substantially comprised of a plurality of continuous linear and curvilinear solid projections, or ridges, which are rigidly attached to and project perpendicularly and downwardly from the obvert side of the tray. The vertical solid ridges help stiffen the tray without adding substantial weight thereto.
The ridges projecting from the obvert side of the tray are connected end-to-end to form a variety of geometric shapes such as triangles, rectangles and circles. Linear ridges which are parallel to a side of the tray are, for convenience, referred to as stringers. Linear ridges which are not parallel to a side of the tray are, for convenience, referred to as ties. Curvilinear ridges are, for convenience, referred to as walls.
The solid ridges on the obvert side of the tray occur in parallel adjacent pairs which cooperate to produce slots there between. The slots can help stiffen the tray, but the principal function of the slots is to slidably receive and protect elements, i.e., ribs, of the structural insert. As further explained below, the principal function of the ribs of the structural insert is to stiffen the deck and to transfer the load placed on the tray to the edges of the deck. The slots thus operate to stabilize the ribs to prevent lateral bending and/or horizontal movement of the ribs to thereby maintain them in the desired operating position which is perpendicular to the plane of the tray.
Slots between adjacent stringers are referred to as stringer slots. Slots between adjacent ties are referred to as tie slots. Slots and openings between adjacent walls and stringers are referred to as wall slots and wall openings.
The cross sections of the stringers and ties and, therefore, of the slots, can form any desired geometric shape, such as rectangular, triangular, circular, xe2x80x9cTxe2x80x9d or any other shape which provides to the tray a combination of low weight and structural integrity.
The ridges, which, as mentioned, cooperate to form the slots to stabilize the ribs, also operate to protect the ribs from potential damage caused by impact with material handling equipment. In this regard, the material of construction of the ridges is flexible in nature and thus exhibits high impact resistance. The tray is, thus, preferably constructed of a material having chemical and physical properties which feature low weight and resistance to abrasive and impact forces caused by handling equipment as well as the load placed thereon. An example of such a material is a recycled or virgin commodity grade plastic, such as high density polyethylene.
The structural insert consists of an upper, i.e., a nesting, side having elements which are adapted to be slidably, but removably, embedded in the obvert side of the tray, and a lower, i.e. a leg, side having elements adapted for slidable, but removable, axial insertion therein of the mentioned legs of the ground support means to enable connection to the deck of the above mentioned base member.
The mentioned nesting elements of the structural insert are substantially comprised of a plurality of linear and curvilinear ribs. The ribs are rigidly and permanently connected at their ends to solid panel points. The combination of ribs and panel points form an open frame work, i.e., a lattice. Linear ribs which are parallel to a side of the structural insert are, for convenience, referred to as stringer ribs. Linear ribs which are not parallel to a side of the structural insert are, for convenience, referred to as tie ribs. Curvilinear ribs are, for convenience, referred to as wall ribs.
Stringer ribs are adapted for slidable insertion into the mentioned stringer slots. Tie ribs are adapted for slidable insertion into the mentioned tie slots. Wall ribs are adapted for slidable insertion into the mentioned wall slots and wall openings. Each of the ribs of the structural insert is shaped to be completely and snugly imbedded in a corresponding slot. Thus, the length of a rib is equal to the depth of the slot into which it is inserted and the width of a rib is equal to or just slightly less than the width of the slot into which it is inserted. Accordingly, after the ribs of the structural insert are nested in the slots of the tray the underside of the deck thereby produced appears to be regular, i.e., lacks material protrusions, and planar in nature.
The material employed in the construction of the structural insert possesses strength sufficient to resist compressive forces exerted by the load placed on the tray which would cause unacceptable deflection of the deck. The selection of the particular material of construction of the structural insert is, thus, principally influenced by the bending strength or flexural modulus and the modulus of elasticity of the material. Flexural modulus relates to resistance to deflection under load, wherein the higher the flexural modulus the greater the resistance to deflection. In contrast, the modulus of elasticity relates to the ability of a material to return to a pre-stressed shape after the release of applied stress. As the elasticity (the modulus of elasticity) of a material increases the ability of the material to resist abrasion also increases, but the ability of the material to resist deflection (the flexural modulus) decreases. However, as the flexural modulus of a material increases the elasticity of the material decreases. Accordingly, the impact properties of the material decreases and it becomes more brittle and subject to cracking caused by static and impact loading. There, thus, exists a need to balance the two material properties to try to optimize the operational results sought in the deck of this invention. In view of the above, the flexural modulus of the material of construction of the structural insert has a value in the range of from about 400,000 to about 1,500,000, and preferably greater than about 800,000 psi.
Materials thus believed to be useful herein to serve as the structural insert include wood, metal, such as steel, glass filled polypropylene and fiberglass. Such materials are known to resist deflection even when subjected to temperatures of about 260xc2x0 F. and greater. Glass filled polypropylene is preferred.
It is evident that the structural insert is preferably constructed of a material different from the material employed in the tray. In this regard, the tray material has greater elasticity and, thus, greater impact resistance than the structural insert material, whereas the structural insert material has a higher flexural modulus and, thus, greater bending resistance than the tray material. The deck is, thus, preferably a combination of materials which have been shaped to store, support and transport a load.
The specific geometric and structural features of the deck are disclosed below.
In another embodiment, the deck is removably connected to a base member having an outer side and an inner side. The base, like the tray and structural insert, is planar in nature and, when connected to the deck, is in alignment with the deck. The base and tray can be constructed of the identical material.
The outer side of the base is adapted to contact an exterior support, such as the ground or a rack.
The inner side of the base, upon connection to the deck, is adapted to enable either direct contact with the leg side of the structural insert, or indirect contact with the leg side by means of legs of variable length. The inner side of the base member is adapted to enable slidable insertion of selected parts thereof into the interiors of the legs. In the instance where the base is not in direct contact with the leg side, and, thus, separated from the structural insert by the mentioned legs, the combination of the deck and base is referred to herein as a pallet.
The planar portions of the pallet, that is, the tray, structural insert and base, can be made from any material known in the art, and by any means known in the art. However, the preferred materials are those which can be formed by molding. Accordingly, the mentioned parts are preferably made by any molding process known in the art.
The legs are members intended to resist compressive forces applied along the linear axis of the member. The interiors of the legs are adapted to enable slidable, but removable, axial insertion therein of selected elements of the inner side of the base member. The legs are preferably extruded polyvinyl chloride which are hollow and cylindrical in shape and are fire retardant.